Hyd oil leak

[eddieirvine]

i changed my trans hys oil probably more than needed, but i don't consider it a waste of time to take care of what i have, I own a Kubota L3940 very nice tractor save me a lot of work, I have to give it a big hug and thank you from time to time! i noticed the other day a bit of a leak close to where the small button you can push in case you get into water some place you can push this with your finger and let water out, never got that deep with mine, Anyway it appears to be comeing out close to that area, One it is not over filled from filling it from the rear end of tractor into transmission fill hole. i use it for mowing 6 acres of grass and have never notice it leaking before, Now i have taken it to my local gas station to get diesel fuel it is about a 2 mile or less trip. when i get on the road i run it about 3/4 throttle to get there and back, here lately I have done this more often this year than i have been doing. My point is when i have it on the road and run it faster than normal which in my mind will do them good to get up and run than not. Well when i get home from fueling up i look the following day and there is probably and oil leak about the size of a beer can circle? i am thinking this is the only time i have seen trans hdy oil leak. I am not sure why but the high rpm and travel speed causes it to do this, it is not near enough to be concerned about but am looking for a reason and thought maybe someone would know or would have had this problem, but it has happened about a half dozen times and every time i find this small amount of oil on the floor, And it is not motor oil it is the Trans Hyd oil because mine is red in color. Thanks

 

[rScotty]

I'm guessing you are running with the transmission oil level clear full... & maybe even a little overfull and getting some foaming through the overflow with full RPM and the heat of road travel. Not a problem.
If it has a tranny dip stick, checking level with the dip stick pushed in.

 

[whitetiger]

i changed my trans hys oil probably more than needed, but i don't consider it a waste of time to take care of what i have, I own a Kubota L3940 very nice tractor save me a lot of work, I have to give it a big hug and thank you from time to time! i noticed the other day a bit of a leak close to where the small button you can push in case you get into water some place you can push this with your finger and let water out, never got that deep with mine, Anyway it appears to be comeing out close to that area, One it is not over filled from filling it from the rear end of tractor into transmission fill hole. i use it for mowing 6 acres of grass and have never notice it leaking before, Now i have taken it to my local gas station to get diesel fuel it is about a 2 mile or less trip. when i get on the road i run it about 3/4 throttle to get there and back, here lately I have done this more often this year than i have been doing. My point is when i have it on the road and run it faster than normal which in my mind will do them good to get up and run than not. Well when i get home from fueling up i look the following day and there is probably and oil leak about the size of a beer can circle? i am thinking this is the only time i have seen trans hdy oil leak. I am not sure why but the high rpm and travel speed causes it to do this, it is not near enough to be concerned about but am looking for a reason and thought maybe someone would know or would have had this problem, but it has happened about a half dozen times and every time i find this small amount of oil on the floor, And it is not motor oil it is the Trans Hyd oil because mine is red in color. Thanks

When you are traveling on the road, do you have the front axle disengaged? You probably have a seep from the front axle propeller shaft seal that is in the front of the transmission case. Running on the road with the front axle engaged can exacerbate the seep.
Having the hydraulic oil level a little over full would not make any difference.

I have repaired several that have never been run down the road, so that is not the only reason they might leak. You have to separate the tractor between the engine and transmission to gain access to the seal for replacement.

 

[JWR]

I do not own a 3940 but assume you have a vent somewhere for the transmission. When it is full (or maybe a little too full) and you run it at a constant higher than you would in regular usage for an extended time -- like to go get fuel -- it may just be building up pressure due to heat and the bubbling process inside causes some overflow through the vent. Same thing rScotty said above I think.

 

[whitetiger]

I do not own a 3940 but assume you have a vent somewhere for the transmission. When it is full (or maybe a little too full) and you run it at a constant higher than you would in regular usage for an extended time -- like to go get fuel -- it may just be building up pressure due to heat and the bubbling process inside causes some overflow through the vent. Same thing rScotty said above I think.

The "VENT" he is referring to is the jiggle pin sticking through the bottom of the clutch housing. It is a dry cavity unless you have a seal leaking oil into it, or get condensation in it.
His transaxle and hydraulic vent to the atmosphere is at the very rear of the tractor.

 

[amhicks21]

i had the same issue with the l3540 that i used to run. its going to be the seal for the shaft to the front axle. the seal itself is a few bucks and easy to put in but requires splitting the tractor. I ended up splitting that tractor myself to save my boss the 1000 bucks and it really wasnt bad to do.

whats important to note is that i only fixed the seal because i work on customers properties and got tired of rigging up diapers and avoiding their pavement. the actual leak was quite minimal and didnt get much worse over 600 hours of use. if you arent in a hurry to fix it, you can just strap an absorbent pad over the case drain and roll with it.

 

[MHarryE]

Like they said, fwd shaft seal. First noticed mine leaking quite a stream, in 2wd, but baling hay which heats the engine and transmission. Next day, after cooling all night, a slow drip until I got transmission hot and it began streaming. Needed tractor bad so took it to my dealer and traded because there were 2 ahead of me same problem.

 

[eddieirvine]

When you are traveling on the road, do you have the front axle disengaged? You probably have a seep from the front axle propeller shaft seal that is in the front of the transmission case. Running on the road with the front axle engaged can exacerbate the seep.
Having the hydraulic oil level a little over full would not make any difference.

I have repaired several that have never been run down the road, so that is not the only reason they might leak. You have to separate the tractor between the engine and transmission to gain access to the seal for replacement.

no i never have it in four wheel drive unless i need it say to load dirt in the bucket or moving snow, other than that i mow in the summer time with it and it stays in two wheel drive or disingausged not a good idea especially running down the road to have it in four wheel drive .

 

[eddieirvine]

responses have sounded good and i am guessing with a topped of oil fill and speed and hot tempuratures is causing this i was not to concerened about it becasue this is the only time i see any leaking, regular mowing and bucket work i never do thanks guys for taking the time with me i appreciate the help and advice!

 

[eddieirvine]

i had the same issue with the l3540 that i used to run. its going to be the seal for the shaft to the front axle. the seal itself is a few bucks and easy to put in but requires splitting the tractor. I ended up splitting that tractor myself to save my boss the 1000 bucks and it really wasnt bad to do.

whats important to note is that i only fixed the seal because i work on customers properties and got tired of rigging up diapers and avoiding their pavement. the actual leak was quite minimal and didnt get much worse over 600 hours of use. if you arent in a hurry to fix it, you can just strap an absorbent pad over the case drain and roll with it.

i can see your thoughts on this but my front i changed the two seals on front wheels and i uaed 80 90 gear oil a better choice in my opinion instead of lighter oil, The reason i am mentioning this is the oil in my transmission and hydraulic is red in color i have used this for my UTD fluid and the leak i have is red oil so it is coming from my hyd trans. the 80 90 oil i put i the front end is clear oil